package tests;

import java.util.Scanner;

public class test19 {
    public static void main(String[] args) {
        long[] arr = new long[80];
        arr[0] = 1;
        arr[1] = 1;
        for(int i = 2;i < 80;i++){
            arr[i] = arr[i-1] + arr[i-2];
        }
        Scanner sc = new Scanner(System.in);
        while (sc.hasNextInt()){
            long count = 0;
            int from = sc.nextInt();
            int to = sc.nextInt();
            for(int i = from-1;i < to;i++){
                count+=arr[i];
            }
            System.out.println(count);
        }
    }
}
